The present invention relates to computer systems and particularly to execution of operations, such as I/O (input/output) operations, for one computer architecture on another computer architecture.
In some computer systems, operations performed on one architecture, such as non-mainframe I/O operations, cannot directly access I/O devices operating according to another architecture, such as mainframe architectures. In such circumstances, the one architecture and the other architecture are not inter-operable. In such systems, access to the data on the I/O devices is provided indirectly for the non-mainframe systems.
In one example, indirect access to the data is provided via a network using Ethernet, TCP/IP, and a network file system (NFS). Because the NFS server is implemented on the mainframe, the mainframe's performance suffers when a non-mainframe platform makes an access to the data. This is because the mainframe has to perform a direct access to the device on behalf of the non-mainframe system and communicate the data to or from the non-mainframe system. Furthermore, both mainframe and non-mainframe suffer network processing overhead.
In another example, an intermediary device is used that supports the ESCON (Enterprise Systems Connection) or FICON (Fiber Connection) protocol (offered by International Business Machines Corporation) on the mainframe side and a network interface on the non-mainframe side. The intermediary device appears to be a direct access storage device (DASD) or channel-to-channel (CTC) control unit to the mainframe. It relays the information transmitted on the mainframe side to the non-mainframe side and vice versa. Use of the ESCON or FICON interface results in lower processing burden on the mainframe than a network attachment on the mainframe. However, the mainframe is still required to make the storage device accesses on behalf of the non-mainframe platform, and the non-mainframe system suffers network processing overhead. Furthermore, the intermediary device adds cost to the solution.